The former U.S. Attorney who prosecuted the case against Gary Lee Sampson, who admitted to killing three people in Massachusetts and New Hampshire, approved of Friday’s news of a second trial seeking the death penalty.

Mike Sullivan, the Plymouth County prosecutor when Sampson confessed to committing the murders in 2001, later became the U.S. attorney when he indicted Sampson in federal court and also sought the death penalty against him.

On Friday, Sullivan said the government should follow the same path against Sampson, a drifter from Abington, it took before.

“I hope they do the exact same thing they did the first time in laying out the horrible aggravating circumstances and allowing the jurors to seek the death penalty,” said Sullivan.

“There was nothing that the government did that contributed to a new trial. You never achieve closure but the criminal case should be final,” said Sullivan.

Federal prosecutors announced Friday they will seek the death penalty through a new trial instead of allowing Sampson to serve a life sentence.

Sampson pleaded guilty to federal charges in the 2001 slayings of 19-year-old Jonathan Rizzo of Kingston and 69-year-old Philip McCloskey of Taunton. He also pleaded guilty to separate state charges in New Hampshire in the death of Robert Whitney of Concord.

In 2003 the federal jury in Boston recommended the death penalty. But the death penalty sentence was tossed out in 2011, after it was discovered that a juror lied during the jury selection process. U.S. District Judge Mark Wolf found that Sampson’s constitutional rights were violated.

Sampson, now 54, became the first person sentenced to death in Massachusetts under the federal death penalty law. Massachusetts does not have a state death penalty. According to Sullivan, if Sampson is sentenced to the death penalty in the second trial, prosecutors would probably ask that Sampson be executed in a federal facility.

Prosecutors said they intend to ask for a date for a new penalty hearing during a court status conference scheduled in January.

“Every murder case is horrible, but this ranks up there as worst of the worst,” said Sullivan.